1. Field of the Invention
The present invention relates to an ink jet recording apparatus for recording by discharging ink to a recording medium.
2. Related Background Art
A recording apparatus provided with the functions of a printer, copying machine, facsimile, and the like or a recording apparatus used as an output equipment for a complex electronic apparatus or a work station including a computer, word processor, and the like, is structured to record images on a sheet paper, thin plastic sheet, or some other recording material (recording medium). These recording apparatuses can be classified into an ink jet type, wire-dot type, thermal type, laser beam type, and others depending on the recording methods adopted for them, respectively.
Generally, with the recording apparatus of the serial type that adopts a serial scanning method for performing the main scan in the direction substantially perpendicular to the feeding direction (sub-scanning direction) of a recording material, images are recorded on the recording material in the main scanning direction by causing a carriage having a recording head, serving as recording means, mounted on it to travel on the recording material after the recording material has been set at a given recording position.
Then, when a recording on one line portion is completed, a sheet feeding (pitch feed) is performed for a given amount. After that, the recording of images is resumed in the main scanning direction for the next line of the recording material the movement of which has been suspended until then.
By repeating the operation described above, the recording is executed on the entire area of the recording material.
Of the recording apparatuses, its possible to obtain the advantages given below by adapting a recording apparatus of an ink jet type (an ink jet recording apparatus) that records on a recording material by discharging ink from the recording head serving as recording means.
(1) Recording means can be fabricated compactly with ease.
(2) Highly precise images can be recorded at high speeds.
(3) Recording can be performed on an ordinary paper without any particular treatment given thereto.
(4) Running costs are low.
(5) Being non-impact type, the apparatus can operate with a lesser amount of noises.
(6) Color images can be recorded with ease by use of multiple color ink.
Also, for the recording apparatus of a line type that uses a line type recording head provided with many numbers of discharge ports arranged therefor in the sub-scanning direction with respect to a recording material, the recording speeds can be enhanced more.
Of the ink jet recording apparatuses described above, recording means (recording head) of an ink jet type that discharges ink by the utilization of thermal energy can be formed easily to provide a highly densified arrangement of liquid paths (arrangement of discharge ports) by the film formation applied to the provision of electrothermal transducing elements, electrodes, walls of liquid paths, ceiling, and others on a base board by means of etching, deposition, sputtering, and other processes of semiconductor fabrication. Also, by making the most of the IC technologies and micro-machining techniques, it is easy to implement the elongation and surfacing (two-dimensional processing) of recording means, hence easily implementing the fully multiple recording means as well as its highly densified assembly.
Meanwhile, there are various demands on the materials of recording media. In recent years, it has been requested to provide a perforated continuous sheet, and paper sheets that have been prepared in arbitrary shapes for use, in addition to the paper sheet usually adopted for recording.
When using the ink jet recording apparatus described above, there are some cases where defective discharges (including disabled ones) are caused due to clogging of the discharge ports if paper particles, dust particles, or other foreign substances adhere to the ink discharge .ports of the recording head or if ink in the discharge ports are dried to become overly viscous or solidified therein. Therefore, in order to prevent the discharge ports from being clogged, a recovery device is adopted for closing the ink discharge ports of the recording head by means of a cap when recording is at rest, and sucking ink from the discharge ports at the same time by suction means such as a pump (not shown) through the cap, thus maintaining the discharge ports in good condition. Here, in case of the ink jet recording apparatus of the serial type described above, the closing operation (capping operation) by means of the cap is executed in such a manner that the recording head is driven to the capping position arranged in a location out of the recording area, and then, the cap and ink discharge ports are caused to be in contact with each other in the capping portion thus arranged.
Also, the ink jet recording apparatus described above is provided with cleaning means for removing foreign substances adhering to the ink discharge ports (the discharge port formation surface) of the recording head. As one example of such cleaning means, there is adopted a mechanism that wipes and cleans the discharge port formation surface of the recording head by use of a flexible wiper blade (wiping member).
FIG. 11 is a perspective view which shows the structure of the principal part of a generally used ink jet recording apparatus provided with a suction recovery device.
The ink jet recording apparatus shown in FIG. 11 is provided mainly with a recording head 501, serving as recording means, having a plurality of discharge ports to discharge ink droplets by use of energy generating means (such as piezoelectric elements, heat generating resistors) incorporated in the recording head; a carriage 502 that mounts the recording head 501 on it and reciprocates in the main scanning direction; a carriage guide shaft 503 that supports carriage 502 slidably; a feed roller 505 that carries (feeds) a recording material 504 in accordance with recording conditions; a pulse motor 506 that serves as driving sources of the feed roller 505 and an automatic sheet feeder (not shown); a pump carriage 507 that mounts a cap unit to cover (close) the discharge port surface of the recording head 501, which is capable of traveling in parallel to the carriage guide shaft 503; a pump guide shaft 508 that guides the pump carriage 507 to effectuate its parallel traveling; and a returning spring 509 that biases the pump carriage 507 to the right-hand side in FIG. 11. Also, an arm section 507a is provided for the pump carriage 507, and an insertion hole 507b is arranged on the leading end of the arm to receive an extrusion 502a installed on the right side face of the carriage 502. With this structure, the extrusion 502a is inserted into the hole 507b when the carriage 502 travels to the left side in FIG. 11 so as to allow the cap 510 to abut upon the discharge port surface of the recording head 501 under pressure. In this way, the carriage guide shaft 503 checks the rotation of the carriage 502 around this shaft.
With the structure described above, the carriage 502 travels in the direction from the right to left side in FIG. 11. Then the arm section 507a is pressed strongly by the carriage 502 to cause the pump carriage 507 to travel in the direction to the left side along the pump guide shaft. In this way, the rear portion of the cap 510 installed on the pump carriage 507 engages with the rail 511, and then, the cap 510 approaches the discharge port surface of the recording head 501 and abuts upon the surface under pressure as the cap 510 shifts more to the left side by means of the rail 511 formed to be increasingly buckled forward to the front side as it extends to the left side. In other words, when the carriage 502 travels, the cap 510 installed on the pump carriage 507 shifts to the left end portion. Then, due to the configuration of the rail 511 thus formed, the cap 510 is allowed to close the recording head 501 (cause it to be in the capping state).
When the pulse motor 506 is driven in this capping state, a pump cam 513 is driven through a pump gear 512. Further, by means of the pump cam 513, the piston of the pump 514 is driven (thus driving the pump 514). Also, a tube 515 is connected to the pump 514 though a joint. The tube 515 is connected to the interior of the cap 510. As a result, when the pump 514 is driven, while the recording head 501 is positioned in the left end portion, ink is sucked from the discharge ports of the recording head 501 through the tube 515 and cap 510 for the execution of the recovery operation.
Also, in FIG. 11, the wiper (wiping member) 516 for wiping the discharge port surface of the recording head 501 is installed in the location slightly protruding to the traveling path of the recording head 501: such location is on the right side of the pump carriage 507 and on the left side of the feeding path of a recording material 504.
In this way, when the carriage 502 travels to the left side of the feeding path of the recording material 504 to push the pump carriage 507, the discharge port surface (ink discharging portion) of the recording head 501 is being wiped by means of the wiping member 516. Also, when the carriage 502 travels to the recording material 504 side from the pump carriage 507 side, that is, it travels from the left side portion to the right-hand side, the discharge port surface of the recording head 501 is wiped by means of the wiping member 516.
However, for the conventional ink jet recording apparatus described above, the arrangement is made to keep the wiping member always in a state that it is protruded to the traveling path of the recording head. Therefore, when the carriage reciprocates, the discharge port surface of the recording head is wiped each time it travels to the left side or to the right side: the wiping operation is executed twice a reciprocation of the carriage inevitably. Also, in a case of the predischarge that discharges ink into the cap from the recording head without executing any capping, the wiping operation is inevitably performed. This means that the wiping operation is executed even when there is no need for it. Hence, a higher possibility of defective discharges may be brought about by the wiping operation itself or there is a problem of the surface degradation due to wearing of the discharge port surface of the recording head or there occurs the surface degradation of the wiping member or the earlier surface degradation thereof, among some others.
Here, it is conceivable to provide a special driving system so that the wiping member can be protruded or detracted as required. However, the provision of such special driving system results in a significant increase of costs eventually.
Besides this conception, there has been proposed a method for solving the problem described above in such a manner that with the provision of a sliding member that travels in the non-recording area along the traveling of a carriage in the non-recording area, a capping member and a wiping member are arranged to advance to the recording means side and part them from the recording means by utilizing the slanted face formed on the front side of the sliding member, and then, being interlocked with the traveling of the recording means in the same direction in which the wiping has been performed, the wiping member is caused to retract after wiping the ink discharge port surface of the recording means. In this way, the dimension of the non-recording area is made smaller in the width direction as a solution of such problem as described above.
Nevertheless, in accordance with the structure described above, the curved blade of the wiping member is restored to its original shape by the function of its own elasticity the moment it is parted from the recording means. Therefore, ink adhering to the leading end of the wiping member is also parted and caused to spread therefrom by the restoring force of the blade. In this case, the direction in which ink is caused to fly and spread is toward the recording area. Therefore, a problem is encountered that the spread ink adheres to the recording area of a recording material, leading to the degradation of the quality of printed images.